The invention relates to DNA sequences from fimbrial gene clusters of Escherichia coli strain DSM 6601.
Escherichia coli is a gram-negative bacterium that occurs in human and animal intestinal flora as well as outside the intestines. E. coli exists in numerous varieties, which differ as regards capsule antigens, surface antigens and flagella antigens and can therefore be subdivided into numerous serological types. Classification by serotypes, however, does not provide any indication of the different virulence of the microorganisms. Representatives of one and the same serotype can have different pathogenic potential both in the human and in the animal body, ranging in the extreme case from avirulent to highly pathogenic. The E. coli strain DSM 6601 belongs to serogroup O6:K5, and is rated as nonpathogenic to humans or animals.
This strain has two chromosomally encoded fimbrial gene clusters, namely type I (fim) and F1C (foc) gene clusters. It is known that the fimbriae of this strain carry an adhesin. Adhesins are structures that perform an important function in the adhesion of the bacterial organism to other cells.
The main application of fimbrial genes is in analysis and diagnostics. Nevertheless, other possible applications exist in medicine and nutritional physiology and in biotechnology.
Fimbrial genes or their main subunits can be used, for example, to characterize a given strain, and so further studies of the sequence of these genes is needed.
According to the invention, studies have now been performed with E. coli strain DSM 6601, and the obtained DNA sequences of the main subunits fimA (FIG. 1) (SEQ ID NO:1) and focA (FIG. 2) (SEQ ID NO:2) of the fimbriae have been precisely analyzed. The DNA sequences obtained from the strain were subjected to DNA sequence analysis by means of database programs and were compared with the DNA sequences of known strains. Whereas differences compared with the strain AD 110 (SEQ ID NO:3) were found at one location of the DNA sequence in the main subunits focA of strain DSM 6601, differences relative to the comparison strain HB 101 (SEQ ID NO:4) were found at several locations in the DNA sequence of the fimA gene of strain DSM 6601, as FIGS. 1 and 2 show:
For analysis of the two main subunits fimA and focA of the fimbriae of strain DSM 6601xe2x80x94and of the comparison strains AD 110 and HB 101xe2x80x94the corresponding DNA fragments were first amplified from the chromosome of the strains by means of PCR reactions.